The goal of the Cell Biology Core is to make available to members of the Yale DERC instrumentation, technical personnel and expertise for the analysis of cell function in areas of research related to diabetes. More specifically, the Core focuses primarily on imaging techniques at the light and electron microscopic levels, with emphasis on immunocytochemistry and on light microscopy imaging of living cells. "Live" light microscopy, which has undergone several methodological breakthroughs over the last few years, is adding a new' dimension to the understanding of cell function and can provide critically new information on several aspects of cell physiology relevant to diabetes. A Sub-Core will offer expertise and technology for the analysis of phosphoinositide metabolism. Phosphoinositide metabolizing enzymes such as PI 3-kinase and SHIP2 have been shown to play a critical role in controlling insulin responses. The Core will capitalize on expertise at Yale in this field to make available methodology for the quantitative analysis of distinct phosphoinositide species.